Trial of Iloprost in Pulmonary Hypertension Secondary to Pulmonary Fibrosis

* Prospective open labeled observational study * Subjects: About 15 patients with secondary pulmonary hypertension due to IPF or pulmonary fibrosis associated with collagen vascular diseases. * Method: 3 month trial of inhaled iloprost. Check the safty and measure the pulmonary arterial pressure by right heart catheterization, exercise capacity by 6 minute walking test, echocardiography, and quality of life questionnaires before and after the trial.